As I mentionned earlier I’m learning to use Rhino. I’m watching a lot of tutorials and do them, but I need here advices for a topolgy before beginning a new object.
Please find below images of the kind of closed shape with different pronounced curvature I try to do :
Your photos don’t make what you want entirely clear, but as a general solution the “Sweep 1 rail” command is probably a good starting point and you should read the help material on it, then:
Create a cross-sectional outline of the object. Here is a generic example
For the “technical part” you can use the boolean tools to add or subtract other solid parts. Again, check out the help details to see how this works out.
HTH
Jeremy
PS. It would be nice if you edited your Discourse profile to show a friendlier name than user2996!
A mix of straight lines, arcs, an ellipse (split) probably covers it. Join, trim and fillet to assemble, tidy and polish. If you are not yet comfortably familiar with how to do this then go here: Rhino - Learn to use Rhino (rhino3d.com) and start out with the Level 1 Manual - that will give you a more balanced foundation than most YouTube tutorials.
It isn’t clear how you want to use curvature: maybe in the plane of the rail, or perpendicular to it?
Or maybe you mean changing the cross-section to be more rounded at the arrows? - just add more cross-sections in different shapes and the sweep will try to accommodate them.
If you click on your icon on the forum page you can navigate to your preferences and add a name or nickname which better reflects who you are. There are now thousands of people with usernnnn user names which just seems very impersonal.